SQL & PL/SQL :: Inserts Based On Column Values

I have a data in one table with 6 columns where user may be updating values in all of these 6 columns or he may enter 3 or 4 columns based on that inserts should take place, this is similar to my previous thread , i am using if condition to check column for null if its not null then i will make a insert , but is there any other easier way to do this.

CREATE TABLE ot_inspect_head
(inh_sys NUMBER,i_txn_code VARCHAR2(12),i_no NUMBER,i_ref_txn VARCHAR2(20),i_ref_no NUMBER);
CREATE SEQUENCE inh_sys START WITH 1;
CREATE TABLE ot_inspect_item
(ii_inh_sys NUMBER , ii_pi_sys NUMBER,ii_sys NUMBER,ii_item_cd VARCHAR2(12),
ii_grade VARCHAR2(12),ii_qty number, ii_flex_01 VARCHAR2(12),ii_flex01_qty number,
ii_flex_02 VARCHAR2(12),ii_flex02_qty number,ii_flex_03 VARCHAR2(12),ii_flex03_qty number);
CREATE SEQUENCE ii_sys START WITH 1;

insert into ot_po values ('ss-po',1,ph_sys.nextval);
insert into ot_inspect_head values (inh_sys.nextval,'ss-ins',1,'ss-po',1);
commit;
select * from ot_inspect_item

II_INH_SYS II_PI_SYS II_SYS II_ITE II_GRADE II_QTY II_FLEX_01 II_FLEX01_QTY II_FLEX_02 II_FLEX02_QTY
---------- --------- ------ ------ -------- ------ ---------- ------------- ---------- -------------
2 1 2 HEA100 A 100

--Now if the inspection user issues the update statement , it will delete this row
--from ot_inspect_item and reinserts the values with values based on
--ii_flex_01,ii_flex_02,ii_flex_03
[code]...